Phase of an engine camshaft may be adjusted relative to a position of an engine crankshaft. Phase adjustments to the camshaft allow intake and exhaust valves to overlap and utilize internal exhaust gas recirculation (EGR). Further, camshaft phase adjustments provide for late intake valve closing which may increase pushback of gases into the engine intake manifold so that engine pumping losses may be adjusted. Phase of a camshaft may change significantly between different engine operating conditions. If engine speed and load change rapidly without phase of the camshaft following the change in engine operating conditions, engine emissions and power output may degrade during transient conditions. One type of camshaft relies on cam torque to change position. If torque applied to the cam is low, the camshaft phase may not be adjusted as fast as is desired. Consequently, engine emissions, performance, and fuel economy may degrade.
The inventor herein has recognized the above-mentioned disadvantages and has developed a method for operating an engine, comprising: activating one or more deactivated cylinder valves via a controller in response to a request to move an engine camshaft; and adjusting a position of the engine camshaft relative to a position of an engine crankshaft via torque provided via activating the one or more deactivated cylinder valves.
By activating one or more deactivating cylinders in response to a request to move a camshaft, it may be possible to provide the technical result of increasing a rate of camshaft phase adjustment. For example, if several cylinders of an engine are deactivated, spring force acting on the camshaft from valve springs may be reduced. However, by reactivating the cylinder and its valves, the spring force from valves springs may act upon the camshaft to increase a rate that cam phase may be adjusted. Consequently, the camshaft's phase may track closer to a desired phase that is related to the change in engine operating conditions.
The present description may provide several advantages. For example, the approach may reduce vehicle emissions. Further, the approach may provide increase engine performance of an engine with deactivating cylinders. Further still, the approach may improve fuel economy of an engine with deactivating cylinders.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.